Engine temperature responsive means to control fuel supply bypass and spill lines



May 29, 1956 o. N. LAWRENCE 2,747,369

ENGINE TEMPERATURE RESPONSIVE MEANS TO CONTROL FUEL SUP LY BYPASS ANDSPILL LINES Filed Jan. 28, 1953 MANUAL-LY AAm/on' AUTOMATICALLY ops/uBLE VALUME- CONTROL MEANS 11/ 4 EC TR/C J CURRE/V r A MPL lF/ER o D Fig?1:210 BJZZOI" @NLawperzce United States Patent ENGINE TEMPERATURERESPONSIVE MEANS TO COlIROL FUEL SUPPLY BYPASS AND SPILL LIN Owen NapierLawrence, Dorridge, England, assignor to Joseph Lucas (Industries)Limited, Binningham, England Application January 28, 1953, Serial No.333,634

Claims priority, application Great Britain February 13, 1952 2 Claims.(Cl. 60-3938) This invention relates to means for supplying liquid fuelto jet engines, gas turbines, or other like prime movers.

The invention comprises in combination a main path and a by-pass paththrough which fuel can be supplied from a pump to the burner or burnersof the prime mover, the by-pass path being in parallel with a portion ofthe main path, a volume-control means in the main path, a meansresponsive to a pressure difference in the main path for controlling theflow in the by-pass path, a pair of valves in the bypass path, andelectromagnetic means responsive to a temperature associated with theprime mover for actuating the valves, one of these valves serving toclose the by-pass path, and the other serving to divert fuel from themain path to a sump or the inlet side of the pump.

In the accompanying drawings:

Figure 1 is a part sectional view illustrating diagrammatically a systemin accordance with the invention.

Figure 2 is a diagram showing the electromagnetic means employed in thesystem.

In carrying the invention into effect as shown in the drawings, there isemployed any convenient variabledelivery pump a for supplying the liquidfuel to the burner or burners b of the prime mover c along a passageforming a main path d. In the main path is included any manually and/orautomatically operable volume-control means of known form e acting on aliquid-operated servo-mechanism f for controlling the rate of flow offuel from the pump a along this path. The pump a and servo-mechanism fare also of known form, and may be similar to those described in patentspecification No. 2,403,371. The controlling means e, when automaticallyoperable, is responsive to such factors as the speed of the prime mover,atmospheric pressure, and/ or the pressure of the air supplied by ablower, and may be similar to that described in patent specification No.2,567,500. Both the controlling means e and the liquid-operatedservo-mechanism f are of known form, and do not require furtherdescription. In the part of the main path d between the pump a and thecontrolling means e is included a restriction g for setting up apressure difference in the liquid flowing in this part of the path, andthe anterior side of the restriction and the exit side of thecontrolling means are interconnected by a passage forming the by-passpath h.

At a point in the main path d between the said restriction g and thecontrolling means e is connected a passage i leading to one of twocompartments j, k into which a chamber is divided by a flexiblediaphragm m the other compartment k forming a part of the by-pass pathh. On the diaphragm m is carried a closure member n which by cooperationwith a seat in the by-pass path It can control the flow in this path.When the system is at rest the closure member it closes or restricts theby-pass path It at the seat 0, but when flow commences in the main path(1 this by-pass path is opened by the closure member in response to thepressure-difference between the entrance and exit sides of therestriction g.

2,747,369 Patented May 29, 1956 ice In the by-pass path h are includedtwo normally closed valves p, q. The valve p is situated between theentrance to the by-pass path and the seat 0 controlled by the closuremember n above mentioned. The other valve q controls the entrance to aspill path formed by a passage r leading from the by-pass path h to asump or the inlet side of the pump (I. These valves 2, q arerespectively connected to a pair of electromagnets s, t, and areoperable thereby under the control of any convenient electric currentamplifier a which is connected to a thermo-couple y in the prime mover 0so that the amplifier is responsive to the electric current produced bythe thermocouple, and thus to the temperature of the motive fluid in thepart of the prime mover containing the thermocouple. The electromagnet sfor operating the valve p is provided with a pair of opposed windings v,w, and the electromagnet t for operating the other valve q is providedwith a single winding x. Also the winding w of the electromagnet s isconnected in series with the winding x of the electromagnet t, andcurrent is supplied to these windings under the control of the amplifieru which in turn is controlled by a thermocouple y.

When the system above described is brought into operation, current fromany convenient source flows through the winding v of the electromagnets, and causes the valve 1 to be opened, so allowing fuel to flow throughthe bypass path h until a predetermined temperature is reached in thevicinityof the thermocouple At this temperature the current in thewinding w neutralizes the action of the current in the winding v, soallowing the valve p to close under the action of a spring 2. Atachigher temperature in the vicinity of the thermocouple y an increasedcurrent flows through the winding w and the winding x of the otherelectromagnet t, and this causes the other valve q to open against theaction of a spring 3, permitting valve n to close and allowing fuel fromthe main path a to be diverted through the by-pass path it and thepassage r to the sump or pump inlet.

The arrangement is such that when the system is operating under normalworking conditions, the fuel flowing along the main path d is subject tothe control of the controlling means e in the main path. Also the flowin this path is supplemented by fuel flowing along the bypass path h,the rate of flow in the latter path being dependent on the pressuredifference across the restriction g above mentioned. When thetemperature in the vicinity of the thermocouple exceeds a predeterminedamount the valve p in the by-pass path h closes, causing a diminution ofthe total fuel supplied to the engine. Should the temperature continueto increase, then at a predetermined higher temperature the valve qopens, causing fuel to be diverted from the main path a. Alternatively,in some cases, it may be arranged for both valves p, q to be actuatedsimultaneously, that is to say one to close and the other to opensimultaneously.

By this invention the control of the rate of supply of fuel to the primemover can be closely regulated in a convenient manner.

Having thus described my invention what i claim as new and desire tosecure by Letters Patent is:

1. A system for supplying liquid fuel to a jet engine, gas turbine, orlike prime mover, comprising in combination with a fuel pump, a mainpath and a bypass path through which fuel can be supplied from the pumpto the prime mover, the by-pass path being in parallel with a portion ofthe main path, a volume-control means in the main path, means forestablishing a pressure difference in the main path, a means responsiveto the said pressure difference for controlling the flow in the bypasspath, a pair of valves in the by-pass path, a spill path for fuel fromthe main path, and electromagnetic means responsive to a temperature ofthe motive fluid in the prime mover for opening the valves with increaseof the said temperature, one of the valves being located in and servingto close the by-pass path, and the other of the valves being locatedbetween the main path and the spill path and serving, when open, topermit fuel flow from the-main :path to the spill path.

2. A system as claimed in claim 1,:in which the electro- 4 control thevalve for closing the lay-pass path, and the second electromagnet 'beingconnected to and serving to control the other valve.

References Cited J-in the file of this patent UNITED STATES PATENTS2,440,566 Armstrong Apr. 27, 1948 2,590,853 Fulton Apr. 1, 19522,594,689 Sharp Apr. 29, 1952 2,610,466 Ballantyne Sept. 16, 1952

